Side scan sonar imaging system with enhancement

ABSTRACT

A system for use with a boat to provide underwater sonar images, includes a left side scan sonar transducer for transmitting left side scan sonar pulses and for receiving left side scan sonar return signals, a right side scan sonar transducer for transmitting right side scan sonar pulses and for receiving right side scan sonar return signals, and signal processing circuitry for processing the left and right side scan sonar return signals to produce side scan image data. The system further includes a user interface including user inputs and a display and a digital processor for providing signals to the display to show an underwater image based upon the side scan image data, wherein the digital processor, in response to a user command, performs an image enhancement algorithm to enhance the underwater image.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This is a continuation of U.S. patent application Ser. No. 11/195,107,entitled “SONAR IMAGING SYSTEM FOR MOUNTING TO WATERCRAFT,” filed Aug.2, 2005 by David A. Betts et al. and claims the benefit of U.S.Provisional Patent Application No. 60/598,326, filed Aug. 2, 2004, theteachings and disclosure of which are hereby incorporated in theirentireties by reference thereto.

Reference is also made to application Ser. No. ______ entitled “SIDESCAN SONAR IMAGING SYSTEM WITH BOAT POSITION ON DISPLAY” and applicationSer. No. ______ entitled “SIDE SCAN SONAR IMAGING SYSTEM WITH ASSOCIATEDGPS DATA”, which are filed on even date and are assigned to the sameassignee as this application.

FIELD OF THE INVENTION

The present invention relates generally to sonar imaging systems for usein sport fishing applications such as in a fish finder, sonar depthsounder, etc., and more particularly to side scan sonar imaging systemsfor imaging of the underwater environment to the sides of the watercraftrather than just below the watercraft.

BACKGROUND OF THE INVENTION

Sonar devices that transmit sound waves have been used previously toobtain information about underwater articles, including fish, structuresand obstructions, and the bottom. The sound waves travel from atransducer mounted to a bottom surface of the vessel through the water.The sound wave transmits from the sonar devices in diverging patterns.The sound waves contact underwater articles, which create return echoes.The transducer receives the return echoes and the sonar device analyzesthe received echoes. A display device displays representations of thereceived echoes, for locating fish and other underwater articles.

Known side scan sonar devices locate the transducer in a vessel towed bythe watercraft (e.g., a “tow fish”). The tow fish is coupled to thesonar display by a long cable. The length of the cable will depend onthe depth of the water and other conditions. For typical applications,the length of the cable is 50 feet or more. Moreover, it is not uncommonfor the cable to be hundreds or even thousands of feet long. As can beappreciated by some having ordinary skill in the art, a fisherman orrecreation user desiring to have side scan images would be hindered bysuch an arrangement. For example, maneuvering or turning of thewatercraft in different directions is difficult, as well as tangling ofthe sonar cable with fishing or other recreational equipment. Such knowntow fish transducers are maintained at a consistent distance from thebottom of the body of water. This distance is intended to providedesired or optimized resolution and field of view. A consistent distanceinhibits, if not prohibits, modifying known transducers for side scanapplications (or mounting known side scan transducers to watercraft)because the distance between the transducer to the bottom of the waterwill vary as the watercraft travels due to the varying depth of thewater.

Accordingly, it would be advantageous to provide a sonar imaging systemthat is coupled to the watercraft, rather than being coupled by aflexible cable and towed behind the watercraft. It would also beadvantageous to provide sonar imaging system mountable to a motor (suchas a trolling motor), a transom of the watercraft, or to the hull of thewatercraft. It would also be advantageous to provide sonar imagingsystem operable at multiple resonant frequencies for optimizedperformance at varying bottom depths. It would be desirable to providefor a sonar imaging system for mounting to a watercraft having one ormore of these or other advantageous features.

BRIEF SUMMARY OF THE INVENTION

In view of the above, it is an objective of the present invention toprovide a new and improved sonar imaging system that is capable of beingconnected to a watercraft, such as a fishing boat. It is a furtherobjective to provide a new and improved sonar imaging system thatprovides imaging of the underwater environment to the sides of thewatercraft. It is a still further object of the invention to provide anew and improved sonar imaging system that additionally provides imagingof the underwater environment below the watercraft.

The system of the present invention realizes several advantages over thetraditional towfish side scan sonar systems. It is more convenientbecause there are no deployment requirements of getting the transducertowfish into the water, no cable handling hassles and tangles, noprecise speed control requirements to keep the towfish at the rightdepth and prevent it from hitting the bottom, no complicated largediameter turn requirements to prevent the towfish from hitting thebottom when you want to turn the boat, and no worries about getting thelines and cable tangled when fishing. The system of the presentinvention can even be used for imaging by a watercraft in reverse.

The system of the present invention is also more secure than thetraditional side scan sonar systems. There is no chance of snagging thetowfish or loss of transducer. Most fishing is done near bottom rises,drop-offs and underwater structures. Most natural and especiallyman-made lakes have rocks, stumps and standing timber that can snag atowfish and cause damage or loss of the equipment.

Additionally, the system of the present invention provides more area ofcoverage. The watercraft mounted transducer of the present inventiondoes not limit the turning radius of the vessel, and it provides theability to image closer to the shore and near structure. This allows forfaster and more complete imaging. The system also provides more accuratetarget locations. Having the transducer mounted to the watercraft allowsfor precise target locations. With a towed side scan system the crew hasto take into account how much cable is deployed and how deep the towfishis to determine how far back behind the boat the target is. With thewatercraft mounted system of the present invention, this is not afactor. To provide even more accurate images, the system of the presentinvention provides the offset necessary to account for the X and Ydistance between the side imaging transducer and the GPS antenna. Thesystem of the present invention also has a better aspect at some targetsbecause, in some cases, the view from the surface can “see” better overrises and into holes than the towed side scan sonar at a fixed distancefrom the bottom. The system of the present invention can also be mountedto smaller watercraft such as canoes, kayaks and other personalwatercraft.

In a preferred embodiment of the present invention, the system includesfeatures to correct for watercraft mounted nature of the transducers.Unlike using a towfish in which data collection takes place at a fixeddistance from the bottom (same aspect angle at any depth of water), andin which the towfish dynamics are decoupled from vessel motion in roughseas, the system of the present invention compensates for thesedifferences. In a preferred embodiment of the present invention, thedepression angle of the side imaging elements is increased from about 20degrees to about 30 degrees. This provides better coverage at thegreater aspects. Also in a preferred embodiment, the side elements aredesigned to be dual frequency to provide a trade-off between area ofcoverage and resolution. Transducer element shielding and softwarefilters are also provided in a preferred embodiment to eliminate vesselnoise sources such as spark plug and electrical system EMI (solenoids,VHF radios, electric motors, etc.). In one embodiment of the presentinvention, the system includes passive yaw, tilt transducer minimizationor compensation using floating oil bath self leveling. In anotherembodiment the system includes active yaw, tilt transducer minimizationor compensation via tilt sensors and motors.

Additional features over traditional side scan provided by embodimentsof the present invention include fish identification and alarm in sidebeams. Typical side scan systems consider fish as unwanted noise. Screencapture and playback functioning like a digital camera with the abilityto store an image, review already stored images, erase unwanted images,and download images to a computer are also provided in embodiments ofthe present invention. Unlike typical data recording when a user sees animage on the screen they can simply push a capture button, instead ofhaving to start recording before the user sees the target. Preferredembodiments also provide zoom capability that allows a user to view onlythe right or left side at a time and also zoom into a particular areaeither using the cursor or a touch screen. Further, the ability to usestandard image enhancement software (algorithms) either in the unit orpost processed is provided to allow for color, contrast, brightness,auto fix, edge detect, etc.

In a preferred embodiment of the present invention, a down beam isprovided along with the side imaging. This provides for more completearound the boat information (both sides and straight down). It is notlimited to a single beam. One embodiment utilizes a 200 kHz/50 kHz dualbeam. Other embodiments may use a quad beam or even six beam. Inpreferred embodiments, at least one view shows both down beam and sideimaging. This provides the ability to better relate length of shadowinformation to the size of the underwater target. It also provides for aquick means for verification of target location. After a target islocated off to a side, the boat can be driven directly over the targetand located in the down beam for precise location.

In a still further preferred embodiment, GPS imaging is also providedwith the side imaging. In such embodiments a cursor mode allows a userto move the cursor over a target of interest on the screen image and seta waypoint for the location of the structure. The GPS history may beused to determine the distance back and the sonar may be used todetermine the distance to the side. The GPS speed can be used to providethe screen scroll rate to provide more accurate front to back targetdimensions. Without GPS or a speed sensor a fast scroll rate and a slowboat speed will elongate targets and a slow scroll rate and a fast boatspeed will shorten targets. The corners of screen captures can be markedso that large area composite mosaic images can be generated in the unitor post processed later. Preferably, one view that shows both sideimaging and navigation information is provided. This makes it easier tofollow tracks and provide efficient area coverage.

In accordance with these objectives, an embodiment of the presentinvention provides a sonar imaging system for a watercraft including atransducer coupled to the watercraft. Preferably, the system includes atleast one side scanning element and at least one bottom scanning elementand an electronic control head unit coupled to the transducer that isconfigured to display sonar images. In one embodiment of the presentinvention, the sonar imaging system includes circular downward acousticelements and rectangular acoustic elements. The present inventionfurther relates to a software filter configured to remove noisegenerated by a spark plug or other operation of a motor for thewatercraft.

Other aspects, objectives and advantages of the invention will becomemore apparent from the following detailed description when taken inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is an isometric illustration of one embodiment of a fishingvessel mounted sonar imaging system of the present invention;

FIG. 2 is an exploded bottom view isometric illustration of anembodiment of a transducer module constructed in accordance with theteachings of the present invention;

FIG. 3 is a side view illustration of the assembled transducer module ofFIG. 2;

FIG. 4 is an end section view of the assembled transducer module of FIG.3 taken about section line 4-4;

FIG. 5 is a partial section view of the housing joint of the assembledtransducer module of FIG. 4 taken at section A;

FIG. 6 is a fully exploded bottom view isometric illustration to thetransducer module of FIG. 2;

FIG. 7 is a partial exploded view isometric illustration of a tophousing assembly showing placement of downward looking sonar elements;

FIG. 8 is a partial exploded view isometric illustration of a tophousing assembly showing placement of downward looking sonar elementsand side scan sonar elements;

FIG. 9 is an exploded isometric illustration of an embodiment of adownward looking sonar element suitable for application in the sonarimaging system of the present invention;

FIG. 10 is an exploded isometric illustration of an embodiment of a sidescan sonar element suitable for application in the sonar imaging systemof the present invention;

FIG. 11 is an isometric illustration of one embodiment of a cableattachment for the sonar imaging system of the present invention; and

FIG. 12 is a simplified system block diagram of an embodiment of thesonar imaging system of the present invention.

FIGS. 13-18 show examples of sonar images as they appear on a displayscreen.

FIG. 19 shows a display screen showing an underwater environment usingsonar images from both side scan elements and sonar returns from adownward sonar element.

While the invention will be described in connection with certainpreferred embodiments, there is no intent to limit it to thoseembodiments. On the contrary, the intent is to cover all alternatives,modifications and equivalents as included within the spirit and scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the drawings, FIG. 1 illustrates a vessel (shown as awatercraft 10) on a surface 12 of a body of water 14 having a bottom 16.A sonar imaging system 18 is mounted or coupled to the watercraft 10(e.g., rather than being towed by a flexible cable behind the watercraft10) and is configured to scan the water below and to the sides of thewatercraft (i.e., a boat mounted side scan sonar system). The sonarimaging system 18 comprises a transponder or transducer 20 coupled to anelectronic control head unit 22 located at the watercraft 10. The sonarimaging system 18 repetitively scans the body of water 14 for fish andother underwater articles with transmissions of acoustic waves andreceiving and displaying the sonar returns, with the duration ofreceiving being a function of the determined depth from a priortransmission.

Referring to FIGS. 2-11, the transducer 20 includes a housing 24, asonar array (in the form of a plurality of acoustic elements shown asside scan elements 26 and downward scan element 28), a cable 30 couplingthe housing and acoustic elements to the electronic control head unit22. The acoustic elements are configured for acoustic wave transmittingand receiving by a transmitter and a receiver that are operated by theelectronic control head unit 22 for scanning the body of water 14,particularly for locating fish, as well as other underwater articles,and determining characteristics about the bottom 16 (see FIG. 1) of thebody of water. The acoustic or sonar wave beams are transmitted based onthe configuration of the acoustic elements.

The housing 24 comprises a top housing portion 36 and a bottom housingportion 38. The top housing portion 36 includes a pair of mountingmembers 40 extending from the front portion of the top housing portion36. Both top housing portion 36 and bottom housing portion 38 haveprojections extending towards the interior of the housing to providestructural support for the housing assembly, and to provide locating andpositioning support for the acoustic elements. A series of projections42 include v-shaped recesses or notches 44 to form a cradle thatreceives side scan elements 26. Recesses 44 are configured (shaped andpositioned) to support the rectangular shaped side scan elements 26 in aposition and orientation (direction) to provide a particular, desired,predetermined acoustic beam performance.

The housing 24 is coupled to the watercraft 10 by any of a variety ofmethods. The housing 24 is coupled to the watercraft 10 so that thereare no obstructions to either side of the housing (i.e., to block theoperation or affect the performance of the acoustic elements). Accordingto a preferred embodiment, the housing 24 is coupled to the watercraft10 along the centerline of the watercraft so that the housing 24 extendsabout 0.25 inches below the watercraft. According to an exemplaryembodiment, mounting members 40 of the top housing 36 are coupled to amounting bracket 46 that is coupled to a trolling motor. According to analternative embodiment, the mounting members 40 are mounted through thehull of the watercraft 10 (e.g., with a support shaft passing through ahole in the hull). According to an alternative embodiment, the mountingmembers are coupled to a bracket that is coupled to a transom of thewatercraft 10. Alternatively, the housing may be coupled to thewatercraft at any of a variety of positions and at any of a variety ofdepths below the surface of the water. The top housing portion 36 may becoupled to the bottom housing portion 38 by any of a variety ofconventional methods (e.g., snap fit engagement, adhesive, ultrasonicwelding, fusion, heat welding, fasteners such as screws, bolts, rivets,or the like). As illustrated in FIG. 5, one embodiment of the housing 24utilizes a mounting rib 25 that is received in a mounting channel 27 tolocate the top and bottom housing portions 36, 37 together. In oneembodiment, the rib 25 is welded into the channel 27 such as, e.g. viaultrasonic welding or the like.

The side scan elements 26 are located along the sides of the housing 24and are configured to scan the water to the sides of the transducer 20(and watercraft 10) with sonar or acoustic beams 47.

The dimensions of side scan elements 26 are configured to provide thedesired sonar beam pulse 47. The size of the wave front created by thetransmitted acoustic beam affects the resolution of the return echo andthus the quality of the imaging of subsurface articles displayed by thesonar device. Generally, a wide beam provides diffused return echoesthat are particularly suited for indicating the presence of fish in awide area around the watercraft. The signal displayed for fish isreferred to as a “fish arch” or other indicia or icon. A narrower beamon the other hand provides a more detailed return echo or signalrepresentative of the subsurface article. The narrow beam covers asmaller area but provides additional definition of the article. A widerbeam accordingly is useful for providing indications of the presence ofschools of fish in a wide area around the vessel as well as otherunderwater articles. The narrow beam is useful for providing details ofthe underwater article or the bottom.

A sonar beam becomes narrower (thereby providing better resolution) asthe corresponding dimension of the acoustic element becomes larger, anda sonar beam becomes wider as the corresponding dimension of theacoustic element becomes smaller (e.g., a small height provides for abeam with a relatively wide vertical angle, and a large length providesfor a beam with a relatively narrow horizontal angle). According to anexemplary embodiment, the side scan elements 26 are configured toprovide a narrow horizontal beam width and a wide vertical beam width.According to a preferred embodiment, the side scan elements have arectangular shape. According to a particularly preferred embodiment, therectangular shaped side scan elements 26 are between about 3 inches toabout 7 inches long by between about 0.125 inch and about 0.50 inchwide. According to a particularly preferred embodiment, the rectangularside scan elements 26 are about 4.5 inches long and about 0.25 inchwide. In such a particular preferred embodiment shown schematically inFIG. 1, the side scan elements 26 transmit the acoustic beam 47 with ahorizontal angle 49 of about 2 degrees and a vertical angle 51 of about50 degrees.

Referring to FIGS. 1, 4, 6, and 7, the side scan elements 26 aresupported (e.g., captured, cradled, secured, etc.) by projections 42 inhousing 24 so that their exposed surface 48 is orientated at apredetermined direction and angle. According to an exemplary embodiment,the side scan elements 26 are supported by the housing so that theexposed surface is orientated outward from the transducer 20 and towardthe bottom of the water (e.g., downward from the watercraft 10 andsurface of the water). According to a preferred embodiment, side scanelements 26 are angled downward between about 20 degrees and about 40degrees, depending on the resonant frequencies. According to aparticularly preferred embodiment, the side scan elements 26 areorientated downward at about 30 degrees for resonant frequencies ofbetween about 260 KHz and about 462 KHz. According to alternativeembodiments, the side scan elements are mounted with any of a variety oforientations and directions, depending on types of depths the transduceris intended to be used in (e.g., lake, river, ocean, etc.) and on theconfiguration of the transducer sonar beams (e.g., as determined by thesize and dimensions of the acoustic elements). Preferably, the side scanelements 26 are coupled to the housing 24 with an epoxy. Alternatively,the side scan elements are coupled to the housing by any of a variety ofadhesives or bonding or joining materials or techniques.

According to a preferred embodiment, side scan elements 26 are made froma piezoelectric ceramic. According to a particularly preferredembodiment, the side scan elements are composed of lead zirconatetitanate (“PZT”) commercially available from Morgan Electro Ceramics ofthe United Kingdom. According to alternative embodiments, the side scanelements may be made from any of a variety of piezoelectric materialscapable of converting electric energy into mechanical energy andconverting mechanical energy into electrical energy.

An acoustic shield 50 (e.g., shielding, decoupler, barrier, absorber,etc.) surrounds all but one side of side scan elements 26 to preventsonar pulses from being transmitted, and sonar returns received by,acoustic elements in all but the desired direction of scanning. Theacoustic shield 50 may be made from any of a variety of materials thatare poor conductor of sonar energy, such as cork, foam, polymers, orother low density materials, and the like.

The downward scan element 28 is located along the bottom middle of thehousing 24 and is configured to scan the water below the transducer 20(and watercraft 10) with sonar or acoustic beams 53 (see FIG. 1).According to a preferred embodiment, downward scan element 28 comprisesa pair of transducer elements coupled together. According to alternativeembodiments, the downward scan element comprises a single element ormore than two elements.

The dimensions of downward scan element 28 are configured to provide adesired sonar beam pulse. According to an exemplary embodiment, thedownward scan element 28 is configured to provide a relatively narrowsonar beam (e.g., for desired or optimum resolution). According to apreferred embodiment, the downward scan elements 28 have a cylindricalshape. According to a particularly preferred embodiment, the cylindricalshaped downward scan elements 28 have a diameter of between about 1 inchto about 2 inches and a height of between about 0.2 inches and about 0.5inches. According to a particularly preferred embodiment, thecylindrical downward scan element 28 has a diameter of about 1.67 inchesand a height of about 0.425 inch. In such a particular preferredembodiment shown in FIG. 1, the downward scan elements 28 transmit theacoustic beam 53 with an angle 55 of about 20 degrees. According toalternative embodiments, the side scan elements and the downward scanelements may have any of a variety of dimensions, positions, andorientations based on desired performance, manufacturing, and costs.

The downward scan element 28 are supported (e.g., captured, cradled,secured, etc.) by projections 52 in housing 24 so that its exposedsurface 54 is orientated at a predetermined direction and angle.According to an exemplary embodiment, the downward scan elements 28 aresupported by the housing so that the exposed surface is orientatedvertically downward from the transducer 20 and toward the bottom of thewater. Preferably, the downward scan elements 28 are coupled to thehousing 24 with an epoxy. Alternatively, the downward scan elements arecoupled to the housing by any of a variety of adhesives or bonding orjoining materials or techniques.

According to a preferred embodiment, the downward scan element 28 aremade from a ceramic. According to a particularly preferred embodiment,the downward scan element 28 are composed of lead zirconate titanate(“PZT”) commercially available from Morgan Electro Ceramics of theUnited Kingdom. According to alternative embodiments, the downward scanelements may be made from any of a variety of piezoelectric materialscapable of converting electric energy into mechanical energy andconverting mechanical energy into electrical energy.

An acoustic shield 56 (e.g., shielding, decoupler, barrier, absorber,etc.) surrounds all but one side of the downward scan elements 28 toprevent sonar pulses from being transmitted, and sonar returns receivedby, acoustic elements in all but the desired direction of scanning. Theacoustic shield 56 may be made from any of a variety of materials thatare poor conductor of sonar energy, such as cork, foam, polymers, orother low density materials, and the like.

The return sonar signal from the bottom reflection carries details aboutthe bottom 16. The return sonar signal from the side reflection carriesdetails about the sides and bottom 16 to the side of the watercraft 10.The sonar return data is communicated or sent to be processed by thetransducer 20 to the electronic control head unit 22 for display ofimages or symbols representative of the received return echoes of theacoustic wave beams. The transmission of an acoustic pulse and thereception of reflected echoes is a transmit/receive cycle, which isreferred to herein as a T/R cycle. The wavefront of the acoustic pulsetravels from the transducer 20, to the bottom 16 of the body of water14, and reflects back to the transducer which receives the reflectedechoes of the acoustic wave beam. The duration of the T/R cycle dependson the depth of the water. Typically, the T/R cycles of transmission andreception are two to four times per second for deep water and morefrequently, such as one-thirtieth of a second, for shallower waters.

According to a preferred embodiment, the transducer 20 does not includeany electronics; rather the electronics are located in the electroniccontrol head unit 22. The images include a bottom profile, objects alongthe bottom or in the water (e.g., fish), and the like. The display mayalso display informational subject matter (e.g., depth, watertemperature, velocity of the watercraft 10, etc.).

Referring to FIG. 12, the electronic control head unit 22 is coupled toa power supply and comprises a user interface (58, 60 and 62), amicroprocessor 64, a co-processor 66, a first side scan circuit 68, asecond side scan circuit 70, and a bottom scan circuit 72. The userinterface is configured to allow for user inputs through a display menuwhere parameters like depth range, sensitivity, fish alarm and the like.The user interface is shown to comprise a keypad 58, buzzer 60, anddisplay 62. Alternatively, the user interface may have switches or pushbuttons, or the like.

The microprocessor 64 is coupled to the user interface and is configuredto process the data from the co-processor 66 (e.g., control thedisplayed information, format the information for display, run theoperational algorithms, and the like). The microprocessor 64 can be amicrocontroller, application-specific integrated circuit (ASIC) or otherdigital and/or analog circuitry configured to perform variousinput/output, control, analysis, and other functions described herein.In one embodiment, the micro-processor 64 includes a memory (e.g.,non-volatile memory) configurable with software to perform the functionsdisclosed herein. The microprocessor 64 of the electronic control headunit 22 implements programmed algorithms (e.g., differential amplitudefiltering (eliminate engine spark noise), time variable gainoptimization—for best image, fish finding algorithms, anti-ringing pulseon transmit for better resolution, and use down beam depth to correctslant angle range information). According to a preferred embodiment, asoftware filter algorithm is provided to filter certain noise common tooperation of watercraft (and noise caused by sparkplug in particular).

During operation of the sonar imaging system 18 in a particularlypreferred embodiment, amplitude readings are taken approximately every0.75 inches, such that 100 feet of depth has 1600 readings. The 0.75inch amplitude readings from the last transmit/receive cycle (T/R cycle)are saved into computer memory. For each of these 0.75 inch amplitudereadings, present and previous amplitude readings the software conductsthe following test: Is “present reading”−“previous reading”>x. If Yes,then substitute “previous reading” for “present reading”. If no, use thepresent reading. The microprocessor 64 also filters the signals, sortssonar target returns from the bottom and fish, calculates display rangeparameters and then feeds the processed signals to the LCD displayscreen. The display 62 is preferably a graphic display, for example, butnot limited on the pixel order. Other displays such as LED, flasher,A-scope and digital segment may alternatively be used. The electroniccontrol head unit 22 may be powered by batteries (e.g., its owndedicated batteries, marine battery, etc.).

The co-processor 66 is coupled to the microprocessor 64 and isconfigured to collect, process, and pass data to the microprocessor 64(e.g. generates the transmission frequencies, converts the analog datato digital with A/D converter and sends to the microprocessor 64). Theco-processor 66 can be a microcontroller, application-specificintegrated circuit (ASIC) or other digital and/or analog circuitryconfigured to perform the functions disclosed herein. In one embodiment,the co-processor 66 includes a memory (e.g., non-volatile memory)configurable with soft-ware to perform the functions disclosed herein.

The first side scan circuit 68 is coupled to the co-processor 66 and isconfigured to operate one of the side scan elements. The first side scancircuit 68 comprises a receiver 74, a transmitter 76, and atransmit/receive switch (i.e., T/R switch 78). The second side scancircuit 70 is coupled to the co-processor 66 and is configured tooperate the other side scan element. The second side scan circuit 70comprises a receiver 86, a transmitter 88, and a transmit/receive switch(i.e., T/R switch 90). The bottom scan circuit 72 is coupled to theco-processor 66 and is configured to operate the bottom scan element.The bottom scan circuit 72 comprises a receiver 80, a transmitter 82,and a transmit/receive switch (i.e., T/R switch 84).

The receivers 74, 80, 86 are configured to amplify the signal andconducts signal filtering, base banding-rectification (e.g., removecarrier frequency), and logarithmic conversions (e.g., to obtain a widerange at output) and preferably provide variable receiver bandwidth. Thetransmitters 76, 82, 88 are configured to drive the acoustic elementsand preferably provide variable transmit power and preferably at a highvoltage. The T/R switches 78, 84, 90 are configured to switch the firstside scan circuit 68 between transmit and receive modes.

According to a preferred embodiment, the electronic control head unit 22is configured to operate at one or more resonant frequencies, dependingon the intended depth and desired resolution. Such a multiple-frequencyoperation is intended to make up for shortcomings of mounting thetransducer to the watercraft 10 caused by the varying distance betweenthe transducer to the bottom 16 of the water 14. According to aparticularly preferred embodiment using a dual-resonant frequency andside scan acoustic elements that are about 4.5 by about 0.25 inch, theelectronic control head unit 22 is configured to operate at 260 kHzresonant frequency (e.g., wider acoustic wave beam for deeper depth andfurther distances) and at 462 kHz resonant frequency (e.g., narroweracoustic wave beam for shallower depth and shorter distances). The downbeam that is provided in one embodiment utilizes a 200 kHz 150 kHz dualbeam. Other embodiments may use a quad beam or even six beam. Inpreferred embodiments, at least one view of the display shows both thedown beam imaging and side imaging. This provides the ability to betterrelate length of shadow information to the size of the underwatertarget.

FIG. 1 shows a cross-sectional view of the body of water 14 toillustrate features of the present invention during operation of thesonar imaging system 18. With additional reference to FIG. 12, the sonarimaging system 18 transmits the acoustic wave beam 47 from the side scanelements 26 and the acoustic wave beam 53 from downward scan elements28. The receivers 74, 80, 86 begin listening for sonar returns throughthe transducer 20. The acoustic wave beams 47, 53 propagate to thebottom surface 16 and reflects a sonar return. The transducer 20communicates the received sonar return to the receivers 74, 80, 86. Aprior cycle had determined the depth, and in the illustrated embodiment,the depth is displayed on the display 62 as well as provided to acontroller for evaluating the duration. Using the prior determineddepth, a controller determines an approximate travel time for the soundenergy signal 47, 53 to reach the bottom 16 and return. At apredetermined proportion of the travel time, the return sonar reaches apoint near the transducer. The return sonar from the bottom 16reflection carries details about the bottom 16. The controller directsthe switch to change the receiving mode from transmit mode to receivemode. The receivers 74, 80, 86 then use the acoustic elements for thereturn sonar. The sonar imaging system 18 continues receiving in thenarrow acoustic wave beam mode, until the start of the next T/R cycle.The received sonar returns are processed by the controller for displayof representative symbols on the display 62. The T/R cycle then repeatswith the newly determined depth from the prior cycle.

The sonar images from the down beam and side scan elements are thendisplayed on the display 62. These images may be shown in grey-scale orin color. The location of the watercraft 10 is also shown in the image.If the user chooses to only display the down beam sonar information,historic information is typically shown to the left of the location ofthe watercraft. As such, the display 62 shows images to the bottom ofthe watercraft 10 that are even with and behind the watercraft 10 whenthe watercraft 10 is traveling forward. The user may also display onlythe side scan sonar images, only those from one side scan element, orimages from both sides and the bottom. The display 62 may also beconfigured (or configurable) to indicate information such as depth, andspeed of the watercraft 10, range, etc.

In a highly preferred embodiment, a GPS receiver 92 is also included toprovide the microprocessor 64 location information. This information maybe used to provide charting and other navigational functions. To provideeven more accurate images, the system of the present invention providesthe offset necessary to account for the X and Y distance between theside imaging transducer and the GPS antenna. In one embodiment a cursormode allows a user to move a cursor on the display 62 over a target ofinterest on the screen image and set a waypoint for the location of thestructure. The GPS history may be used to determine the distance backand the sonar may be used to determine the distance to the side. The GPSspeed is used in one embodiment to provide the screen scroll rate toprovide more accurate front to back target dimensions. Without GPS or aspeed sensor a fast scroll rate and a slow boat speed will elongatetargets and a slow scroll rate and a fast boat speed will shortentargets. The corners of screen captures can be marked so that large areacomposite mosaic images can be generated in the unit 22 or postprocessed later. Preferably, one view that shows both side imaging andnavigation information is provided. This makes it easier to followtracks and provide efficient area coverage.

Referring to FIGS. 13-18, exemplary sonar images 92 reproduced from adisplay 62 are shown in grey-scale. Alternatively, the display 62 maydisplay color sonar images. The location of the watercraft 10 is shownas “0” in the images 92. Historic information is shown to the left of“0”. As such, the display 62 shows images 92 to the bottom or side ofthe watercraft 10 that are even and behind the watercraft 10. A range105 to the side of the watercraft 10 is also provided. A dark area 106along the top of the display 62 shows the water column above the bottom16. The portion 93 of the image 92 below the water column dark area 106shows returns from the bottom 16. As shown by the returns in the sonarimages 92, the body of water 14 includes the bottom 16 and underwaterarticles such as trees 94, logs 96, a sunken barge 98, and a school offish 100. Shadows 102 from the underwater articles indicate the generaldistance or displacement of the underwater article (e.g., distance itextends from the bottom 1). Dark areas 104 typically indicate drop offs,holes, and the like. The display 62 may also be configured (orconfigurable) to indicate information such as depth 108, and speed 110of the watercraft 10.

According to a preferred embodiment shown in FIG. 19, the display 62 isconfigurable to provide an image 120 that shows the underwaterenvironment using both side scan elements (views) 26 and the downwardscan element 28. An icon 122 (in the form of a schematic watercraft)indicates the position and orientation and direction of travel of thewatercraft 10.

It is important to note that the terms are intended to be broad termsand not terms of limitation. These components may be used with any of avariety of products or arrangements and are not intended to be limitedto use with fish finding applications. For example, mounting to awatercraft is not intended to be limiting to devices that are directlyattached to the watercraft, but would include devices attached to motors(such as trolling motors) attached to the watercraft, and the like.

It is also important to note that the construction and arrangement ofthe elements of the sonar imaging system for mounting to a watercraft asshown in the preferred and other exemplary embodiments are illustrativeonly. Although only a few embodiments of the present invention have beendescribed in detail in this disclosure, those skilled in the art whoreview this disclosure will readily appreciate that many modificationsare possible (e.g., variations in sizes, dimensions, structures, shapesand proportions of the various elements, values of parameters, mountingarrangements, materials, colors, orientations, etc.) without materiallydeparting from the novel teachings and advantages of the subject matterrecited in the claims. For example, the transducer preferably providesdual frequency, single element side beams in the form of two opposedvertical beams optimized for range and depth and front to back beamwidth selected based on image resolution, fish finding and transducerlength.

Elements shown as integrally formed may be constructed of multiple partsor elements show as multiple parts may be integrally formed, theoperation of the interfaces may be modified or otherwise varied, thelength or width of the structures and/or members or connector or otherelements of the system may be varied, the nature or number of adjustmentpositions provided between the elements may be varied (e.g. byvariations in the number of engagement slots or size of the engagementslots or type of engagement). It should be noted that the elementsand/or assemblies of the system may be constructed from any of a widevariety of materials that provide sufficient strength or durability, inany of a wide variety of colors, textures and combinations. Accordingly,all such modifications are intended to be included within the scope ofthe present invention as defined in the appended claims.

The order or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. In the claims, anymeans-plus function clause is intended to cover the structures describedherein as performing the recited function and not only structuralequivalents but also equivalent structures. Other substitutions,modifications, changes and/or omissions may be made in the design,operating conditions and arrangement of the preferred and otherexemplary embodiments without departing from the spirit of the presentinvention as expressed in the appended claims.

All references, including publications, patent applications, and patentscited herein are hereby incorporated by reference to the same extent asif each reference were individually and specifically indicated to beincorporated by reference and were set forth in its entirely herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) is to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycon-text. The terms “comprising,” “having,” “including,” and“containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. Recitation ofranges of values herein are merely intended to serve as a shorthandmethod of referring individually to each separate value falling withinthe range, unless otherwise indicated herein, and each separate value isincorporated into the specification as if it were individually recitedherein. All methods described herein can be performed in any suitableorder unless otherwise indicated herein or otherwise clearlycontradicted by context. The use of any and all examples, or exemplarylanguage (e.g., “such as”) provided herein, is intended merely to betterilluminate the invention and does not pose a limitation on the scope ofthe invention unless otherwise claimed. No language in the specificationshould be construed as indicating any non-claimed element as essentialto the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A method of providing underwater sonar images, the method comprising:transmitting left and right side scan sonar pulses with left and rightside scan sonar transducers, respectively; receiving left and right sidescan sonar return signals with the left and right side scan sonartransducers, respectively; generating side scan image data from the leftand right side scan sonar return signals; displaying an underwater imagebased upon the side scan image data; receiving a user command; applyingan image enhancement algorithm to the side scan image data in responseto the user command; and displaying an underwater image based uponenhanced side scan image data.
 2. The method of claim 1, wherein theimage enhancement algorithm comprises user adjustable time variable gainoptimization.
 3. The system of claim 1, wherein the image enhancementalgorithm comprises a fish finding algorithm to differentiate betweenside scan sonar return signals from fish and other side scan sonarreturn signals.
 4. The method of claim 4, and further comprising:transmitting down beam sonar pulses with a down beam sonar transducer;receiving down beam sonar return signals with the down beam sonartransducer; and generating down beam depth values based upon the downbeam sonar return signals, wherein the image enhancement algorithm usesdown beam depth values to correct slant angle range information.
 5. Themethod of claim 1, wherein the left and right side scan sonartransducers are mounted to a boat, and wherein the image enhancementalgorithm comprises differential amplitude filtering to filter certainnoise common to boat operation.
 6. The method of claim 5, wherein eachof the left and right side scan sonar transducers are mounted to theboat in a position that detects noise caused by spark plug operation,and wherein the certain noise comprises spark plug noise.
 7. The methodof claim 1, and further comprising: providing anti-ring pulses upontransmission of the left and right side scan sonar pulses to improveresolution of the underwater image.
 8. A method of providing underwatersonar images, the method comprising: transmitting left and right sidescan sonar pulses with left and right side scan sonar transducers,respectively; providing anti-ring pulses with the left and right sidescan sonar pulses; receiving left and right side scan sonar returnsignals with the left and right side scan sonar transducers,respectively; generating side scan image data from the left and rightside scan sonar return signals; and displaying an underwater image basedupon the side scan image data.
 9. The method of claim 8, wherein theleft side scan sonar pulses are directed downward and laterally outwardto a left side of a boat, the left side scan sonar pulses having anarrow horizontal width in a direction of travel of the boat and a widevertical width in a plane perpendicular to the direction of boat travel,and wherein the right side scan sonar pulses are directed downward andlaterally outward to a right side of the boat, the right side scan sonarpulses having a narrow horizontal width in the direction of travel ofthe boat and a wide vertical width in the plane perpendicular to thedirection of boat travel.
 10. A system for use with a boat to provideunderwater sonar images, the system comprising: a left side scan sonartransducer for transmitting left side scan sonar pulses and forreceiving left side scan sonar return signals; a right side scan sonartransducer for transmitting right side scan sonar pulses and forreceiving right side scan sonar return signals; signal processingcircuitry for processing the left and right side scan sonar returnsignals to produce side scan image data; a user interface including userinputs and a display; and a digital processor for providing signals tothe display to show an underwater image based upon the side scan imagedata, wherein the digital processor, in response to a user command,performs an image enhancement algorithm to enhance the underwater image.11. The system of claim 10, wherein the image enhancement algorithmcomprises user adjustable time variable gain optimization.
 12. Thesystem of claim 10, wherein the image enhancement algorithm comprises afish finding algorithm to differentiate between side scan sonar returnsignals from fish and other side scan sonar return signals.
 13. Thesystem of claim 10, and further comprising: a down beam sonar transducerfor transmitting down beam sonar pulses and receiving down beam sonarreturn signals, wherein the signal processing circuitry processes thedown beam sonar return signal to produce down beam depth, and whereinthe image enhancement algorithm comprises use of down beam depth tocorrect slant angle range information.
 14. The system of claim 10,wherein the image enhancement algorithm comprises differential amplitudefiltering to filter certain noise common to boat operation.
 15. Thesystem of claim 14, wherein each of the left and right side scan sonartransducers is mounted to the boat in a position that detects noisecaused by spark plug operation, and wherein the certain noise comprisesspark plug noise.